The developer of the blue light-emitting diode filed a suit Thursday against his former employer, demanding 2 billion yen and recognition that the patent on the semiconductor belongs to him.

Shuji Nakamura, now a professor at the University of California, Santa Barbara, filed the suit at the Tokyo District Court against Nichia Corp., where he worked as an engineer until 1999, saying the company earned unreasonable profits through its exclusive use of the patent for the blue LED.

The suit is unique because the credit for the patent is being contested between an outside researcher who was hired by the company and his former employer.